Systems and methods for the fixation or fusion of bone

ABSTRACT

A joint between two bone segments is fused by passing an elongated, rectilinear bone fusion device over a guide pin across the joint and into tight engagement within bores formed in the bone segments, to thereby restrict movement of the elongated bone fusion device across the joint. The elongated, rectilinear bone fusion device also provides bony in-growth within the bores along the exterior surface of the bone fusion device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/162,689, filed Jan. 23, 2014, titled “SYSTEMS AND METHODS FOR THEFIXATION OR FUSION OF BONE,” which is a continuation of U.S. patentapplication Ser. No. 13/078,530, filed Apr. 1, 2011, titled “SYSTEMS ANDMETHODS FOR THE FIXATION OR FUSION OF BONE,” now U.S. Patent ApplicationPublication No. 2011/0184478, which is a continuation of U.S. patentapplication Ser. No. 12/804,516, filed Jul. 22, 2010, titled “SYSTEMSAND METHODS FOR THE FIXATION OR FUSION OF BONE,” now U.S. Pat. No.8,202,305, which is a divisional of U.S. patent application Ser. No.11/136,141, filed May 24, 2005, titled “SYSTEMS AND METHODS FOR THEFIXATION OR FUSION OF BONE,” now U.S. Pat. No. 7,922,765, which is acontinuation-in-part of U.S. patent application Ser. No. 10/914,629,filed Aug. 9, 2004, titled “SYSTEMS AND METHODS FOR THE FIXATION ORFUSION OF BONE,” now U.S. Patent Application Publication No. 2006/003625now abandoned, each of which is herein incorporated by reference in itsentirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD

This application relates generally to the fixation of bone.

BACKGROUND

Many types of hardware are available both for fracture fixation and forthe fixation of bones that are to fused (arthrodesed).

Metal and absorbable screws are routinely used to fixate bone fracturesand osteotomies. It is important to the successful outcome of theprocedure that the screw is able to generate the compressive forceshelpful in promoting bone healing.

SUMMARY OF THE DISCLOSURE

The invention provides bone fixation/fusion devices and related methodsfor stabilizing bone segments, which can comprise parts of the same bone(e.g., fracture fixation) or two or more individual bones(e.g., fusion).The systems and methods include a fixation/fusion device adapted forplacement in association with bone segments.

One aspect of the invention provides a method comprising identifying abone site comprising a first bone segment, a second bone segment, and ajoint between the first and second bone segments. The method includesproviding an elongated bone fusion device having a rectilinear crosssection and including an exterior surface treated to provide bonyin-growth, the elongated bone fusion device including a lumenaccommodating passage over a guide pin. The method includes forming abore in the first bone segment, and forming a bore in the second bonesegment that faces the bore in the first bone segment across the joint.The bores in the first and second segments are each sized and configuredto tightly engage the exterior surface of the elongated bone fusiondevice. The method includes placing in the bore of the first bonesegment a guide pin that extends across the joint into the bore of thesecond bone segment. The method includes fusing the joint by passing theelongated bone fusion device over the guide pin across the joint andinto tight engagement within the bores of the first and second bonesegments, to thereby restrict movement of the elongated bone fusiondevice across the joint and provide bony in-growth within the boresalong the exterior surface of the bone fusion device. The methodincludes removing the guide pin.

Another aspect of the invention provides a joint fusion devicecomprising an elongated device having a rectilinear cross section freeof screw threads and being sized and configured for placement inassociation with a joint between individual first and second bonesegments in response to an axially applied, non-rotational force.

The elongated bone fusion device includes a lumen to accommodate passageover a guide pin during placement and an exterior surface treated toprovide bony in-growth upon placement.

In one embodiment, the rectilinear cross section of the elongated bonefusion device comprises a square.

In one embodiment, the rectilinear cross section of the elongated bonefusion device comprises a rectangle.

In one embodiment, the rectilinear cross section of the elongated bonefusion device comprises a triangle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective alternative views of a bonefixation/fusion device having a bony in-growth and/or through-growthregion of a mesh configuration.

FIG. 2 is a perspective view of an alternative embodiment of a bonefixation/fusion device having a bony in-growth and/or through-growthregion of a beaded configuration.

FIG. 3 is a perspective view of an alternative embodiment of a bonefixation/fusion device having a bony in-growth and/or through-growthregion of a trabecular configuration.

FIG. 4 is a schematic view of a bone fixation/fusion device of the typeshown in FIG. 1, being inserted in association with bone across afracture line or between different bone segments.

FIG. 5 is a schematic view of a bone fixation/fusion device positionedin association with a fracture line or between different bone segmentswith a bony in-growth and/or through growth region extending across thefracture line or space between different bone segments.

FIG. 6 is a front plan view of an alternative embodiment of a bonefixation/fusion device having a bony in-growth and/or bonythrough-growth region, in which the device has a conical configuration.

FIG. 7 is front plan view of an alternative embodiment of a bonefixation/fusion device having a bony in-growth and/or through-growthregion in which the device has a beveled distal tip.

FIGS. 8A and 8B are schematics illustrating the insertion of a bonefixation/fusion device of the type shown in FIG. 6 in association with afracture line or between different bone segments.

FIG. 9 is a schematic illustrating a guidewire being introduced intobone in association with a fracture line or between different bonesegments.

FIG. 10 is a schematic similar to FIG. 9 and illustrating a drill bitbeing introduced over the guidewire.

FIG. 11 is a schematic similar to FIG. 10 and illustrating a bore formedin the bone remaining after withdrawal of the drill bit.

FIG. 12 is a schematic similar to FIG. 11 and illustrating insertion ofa bone fixation/fusion device into the pre-formed bore.

FIG. 13 is an exploded front plan view illustrating the coupling of apair of bone fixation/fusion by threaded engagement.

FIG. 14 is a schematic illustrating a pair of bone fixation/fusiondevices coupled together and inserted in association with a fractureline or between different bone segments.

FIG. 15 is a front plan view illustrating passage of a bonefixation/fusion device through a fenestration in another bonefixation/fusion device.

FIG. 16 is a schematic illustrating the placement of a series of bonefixation/fusion devices in bone.

FIG. 17 is a top plan view of a bone fixation/fusion device positionedin association with a fracture line or between different bone segments.

FIG. 18A is a perspective view of an alternative embodiment of a bonefixation/fusion device having a bony in-growth and/or bonythrough-growth region that extends substantially along the entiredevice.

FIG. 18B is a perspective view of a bone fixation/fusion device similarto FIG. 18A and having a bony in-growth and/or bony through-growthregion that extends along a portion of the device.

FIG. 19 is a top plan view of the bone fixation/fusion device of FIG.18A in positioned in association with a fracture line or betweendifferent bone segments.

FIG. 20 is a top plan view of the bone fixation/fusion device of FIG.18A positioned in association with a fracture line or between differentbone segments and stabilized by fixation screws.

FIGS. 21A to 21F are perspective views illustrating alternativeconfigurations of bone fixation/fusion devices of a type shown in FIG.18A.

FIGS. 22A and 22B are perspective views illustrating alternativeembodiments of the bone fixation/fusion of a type shown in FIG. 18A inwhich the device is profiled.

FIGS. 23A and 23B are perspective views illustrating alternativeembodiments of the bone fixation/fusion device of a type shown in FIG. 1with structural elements that provide an anti-rotational function.

FIG. 24 is a perspective view illustrating an alternative embodiment ofthe bone fixation/fusion device of a type shown FIG. 18A in which thedevice includes a series of grooves providing an anti-rotationalfunction.

FIG. 25 is a perspective view illustrating an alternative embodiment ofthe bone fixation/fusion device of a type shown in FIG. 18A in which thedevice includes a pair of opposing wings providing an anti-rotationalfunction.

FIG. 26 is a perspective view illustrating an alternative embodiment ofthe bone fixation/fusion device of FIG. 18A in which the device includesa pair of opposing flanges providing an anti-rotational function.

FIG. 27 is an exploded view of a pair of coupled bone fixation/fusiondevices that, when fitted together, form a composite bonefixation/fusion device.

FIG. 28 is an assembled view of the composite bone fixation/fusiondevice formed from the assembly of the bone fixation/fusion devicesshown in FIG. 27.

FIG. 29 is a front view of the assembled composite bone fixation/fusiondevice of FIG. 28 positioned in association with a fracture line orbetween different bone segments.

FIG. 30 is a perspective view of an alternative embodiment of the bonefixation/fusion device of a type shown in FIG. 18A with fixation plates.

FIG. 31 is a perspective view of an alternative embodiment of the bonefixation/fusion device of FIG. 30.

Fig of 32 is a side view of an alternative embodiment of a fixationplate having a rounded configuration.

FIG. 33 is a side view of an alternative embodiment of a fixation platehaving a tapered configuration.

FIG. 34 is a perspective view of an alternative embodiment of the bonefixation/fusion device of a type shown in FIG. 18A providing a series ofradially-extending fixation ridges.

FIGS. 35A and 35B are perspective views of a bone fixation/fusion devicehaving a malleable region that can be flared or expanded to providefixation and/or anti-rotation resistance.

FIG. 36 is a front plan view illustrating the drilling of pilot holes inadjacent bone segments, which can comprise a fracture line in the samebone or different bone segments.

FIG. 37 is a front plan view illustrating a cavity bored between thepilot holes to receive a bone fixation/fusion device.

FIG. 38 is a front plan view illustrating the placement of a pair ofguide pins within the bored cavity.

FIG. 39 is a front plan view illustrating the placement of the bonefixation/fusion device into the cavity and removal of the guide pins.

FIG. 40 is a front plan view illustrating the placement of a pair ofopposing c-shaped restraints within the bored cavity.

FIG. 41 is a front plan view illustrating the placement of the bonefixation/fusion device into the cavity within the restraints.

DETAILED DESCRIPTION

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention that may be embodied inother specific structure. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

FIGS. 1A and 1B show representative alternative configurations of adevice 10 sized and configured for the fixation of bone fractures (i.e.,fixation of parts of the same bone) or for the fixation of bones whichare to be fused (arthrodesed) (i.e. fixation of two or more individualbones that are adjacent and/or jointed). For the sake of shorthand, thedevice will sometimes be called a bone fixation/fusion device, toindicate that it can perform a fixation function between two or moreindividual bones), or a fusion function between two or more parts of thesame bone, or both functions. As used herein, “bone segments” or“adjacent bone regions” refer to either situation, i.e., a fracture linein a single bone or a space between different bone segments.

In the embodiments shown in FIGS. 1A and 1B, the bone fixation/fusiondevice 10 comprises an elongated, stem-like structure. The device 10 canbe formed—e.g., by machining, molding, or extrusion—from a materialusable in the prosthetic arts, including, but not limited to, titanium,titanium alloys, tantalum, chrome cobalt, surgical steel, or any othertotal joint replacement metal and/or ceramic, sintered glass, artificialbone, any uncemented metal or ceramic surface, or a combination thereof.Alternatively, the device 10 may be formed from a suitable durablebiologic material or a combination of metal and biologic material, suchas a biocompatible bone-filling material. The device 10 may be moldedfrom a flowable biologic material, e.g., acrylic bone cement, that iscured, e.g., by UV light, to a non-flowable or solid material.

The bone fixation/fusion device 10 can take various shapes and havevarious cross-sectional geometries. The device 10 can have, e.g., agenerally curvilinear (i.e., round or oval) cross-section—as FIG. 1Ashows—or a generally rectilinear cross section (i.e., square orrectangular or triangular—as FIG. 1B shows for purposes ofillustration), or combinations thereof. As will be described in greaterdetail later (see, e.g., FIGS. 21A to 21F), instead of being shaped likean elongated stem, the body of the bone fixation/fusion device 10 can beless elongated and form more of a flattened, “wafer” configuration,having, e.g., a rectangular, square, or disc shape.

As FIGS. 2 and 3 shows, the bone fixation/fusion device 10 desirablyincludes a region 12 formed along at least a portion of its length topromote bony in-growth onto or into surface of the device 10 and/or bonygrowth entirely through all or a portion of the device 10.

The region 12 can comprise, e.g., through holes, and/or various surfacepatterns, and/or various surface textures, and/or pores, or combinationsthereof. The device 10 can be coated or wrapped or surfaced treated toprovide the bony in-growth or through-growth region 12, or it can beformed from a material that itself inherently possesses a structureconducive to bony in-growth or through-growth, such as a porous mesh,hydroxyapetite, or other porous surface. The device 10 may further becovered with various other coatings such as antimicrobial,antithrombotic, and osteoinductive agents, or a combination thereof. Theregion 12 may be impregnated with such agents, if desired.

The configuration of the region 12 can, of course, vary. By way ofexamples, FIG. 1 shows the region 12 as an open mesh configuration; FIG.2 shows the region 12 as beaded configuration; and FIG. 3 shows theregion 12 as a trabecular configuration. Any configuration conducive tobony in-growth and/or bony through-growth will suffice.

In use (see FIGS. 4 and 5), the bone fixation/fusion device 10 isinserted into a space between two adjacent bone surfaces, e.g., into afracture site in a single bone or between two bones (e.g., adjacentvertebral bodies) which are to be fused together. In FIG. 4, the device10 is shown being tapped into bone through bone segments 14 (i.e.,across a fracture line or between adjacent bones to be fused) with a tap16. The bone may be drilled first to facilitate insertion of the device10. The bony in-growth or through-growth region 12 along the surface ofthe device 10 accelerates bony in-growth or through-growth onto, into,or through the device 10. Bony in-growth or through-growth onto, into,or through the device 10 helps speed up the fusion process or fracturehealing time.

The bony in-growth or through-growth region 12 may extend along theentire outer surface of the device 10, as shown in FIG. 4, or the bonyin-growth or through-growth region 12 may cover just a specifieddistance on either side of the bone segments or fracture line, as shownin FIG. 5.

The size and configuration of the device can be varied to accommodatethe type and location of the bone to be treated as well as individualanatomy.

As FIG. 6 shows, the device 10 can be angled or tapered in a conicalconfiguration. The degree of angle can be varied to accommodate specificneeds or individual anatomy. A lesser degree of angle (i.e., a moreacute angle) decreases the risk of splitting the bone as the device 10is tapped into the bone or the fracture segments 14. The device 10 mayalso include a beveled distal tip 18 to further add in insertion of thedevice 10 into bone, as shown in FIG. 7. As shown in FIGS. 8A and 8B,the conical shape also helps drive the bone segments or fracturefragments together, reducing the gap (G) between the bone segments 14 orfracture segments.

In FIGS. 9 to 12, the device 10 is cannulated, having a central lumen orthroughbore 20 extending through it, to assist in the placement of thedevice 10 within bone. FIG. 1B also shows a cannulated throughbore in adifferent configuration.

In use, the physician can insert a conventional guide pin 22 through thebone segments 14 by conventional methods, as FIG. 9 shows. A cannulateddrill bit 24 can then be introduced over the guide pin 22, as seen inFIG. 10. A single drill bit or multiple drill bits 24 can be employed todrill through bone fragments or bone surfaces to create a bore 26 of thedesired size and configuration. In the illustrated embodiment, the drillbit 24 is sized and configured to create a conical bore 26 similar insize and configuration to the device 10. The bore 26 is desirably sizedand configured to permit tight engagement of the device 10 within thebore 26 and thereby restrict movement of the device 10 within the bore26. The pre-formed bore 26 may be slightly smaller than the device 10,while still allowing the device 10 to be secured into position withinthe bore 26 by tapping. As seen in FIG. 11, the drill bit 24 is thenwithdrawn. The device 10 is then inserted into the bore 26 over theguide pin 22, as FIG. 12 shows. The guide pin 22 is then withdrawn.

Alternatively, the bone fixation/fusion device 10 itself can includescrew-like threads along the body for screwing the device into place. Inthe arrangement, the device 10 be self-tapping. Also in thisarrangement, the device 10 can be cannulated for use with a guide pin22, or it need not be cannulated.

Multiple devices 10 may be employed to provide additional stabilization.While the use of multiple devices 10 will now be described illustratingthe use of multiple devices 10 of the same size and configuration, it iscontemplated that the devices 10 may also be of different size and/orconfiguration, e.g., one device 10 is of a cylindrical configuration anda second device 10 is of a conical configuration.

In many cases, it may be desirable to couple a series of devices 10together, e.g., to provide stabilization over a larger surface area. Aseries of devices 10 may be coupled together be any suitable means,e.g., by a snap fit engagement, or a groove and tab key arrangement, orby a Morse taper fit, or combinations thereof. In one embodiment, aseries of devices 10 are coupled by threaded engagement. As illustratedin FIG. 13, a first device 10A includes a recess 28 at one end providinga series of internal threads 30. In the illustrated embodiment, thefirst device 10 is of a cylindrical configuration, but may be of anydesired configuration. The internal threads 30 couple with a series ofcomplementary external threads 32 on a second device 10B of a similar orof a different configuration to couple the first and second devices 10Aand 10B together.

The devices 10A and 10B are desirably coupled together prior to beinginserted into the pre-formed bore 26. The series of internal andexternal threads 30 and 32 provide an interlocking mechanism thatpermits a series of devices 10 to be stacked and connected to cover alarger area or multiple bone segments 14 (e.g., a bone having multiplefractures) and thereby provides additional stabilization, as seen inFIG. 14.

FIG. 15 illustrates another embodiment in which a device 10′ includes anopening or fenestration 34 to allow another device 10 to pass through,thereby providing additional stabilization. The fenestration 34 can besized and configured to permit another device 10 to be passed throughthe device 10′ at virtually any angle. The fenestration 34 can also besized and configured to limit movement of the second device 10 relativeto the second device 10′.

In use, and as shown in FIG. 16, the physician taps a first device 10′having a fenestration 34 through the bone segments. A second device 10is then inserted (e.g., by tapping) through the fenestration 34 of thefirst device 10′ into place.

It is further contemplated that device 10′ may also be adapted forcoupling with another device 10A (e.g., by a series of external andinternal threads), permitting the devices 10′ and 10A to be additionallystacked and connected, as also shown in FIG. 16.

FIG. 17 illustrates an alternative form of a bone fixation/fusion device100. Similar to the type of bone fixation/fusion device 10 previouslydescribed, device 100 includes a body 106 formed of a durable materialthat is not subject to significant bio-absorption or resorption bysurrounding bone or tissue over time. In other words, the body 106 isintended to remain in place for a time sufficient to stabilize thefracture or fusion site. Such materials are well known in the prostheticarts and include, e.g., titanium, titanium alloys, tantalum, chromecobalt, surgical steel, or any other total joint replacement metaland/or ceramic, sintered glass, artificial bone, any uncemented metal orceramic surface, or a combination thereof. Alternatively, the body 106of the bone fixation/fusion device 100 may be formed from a suitabledurable biologic material or a combination of metal and biologicmaterial, such as a biocompatible bone-filling material. The body 106 ofthe device 100 may be molded from a flowable biologic material, e.g.,acrylic bone cement, that is cured, e.g., by UV light, to a non-flowableor solid material.

The body 106 of the device 100 may also include a bony in-growth orthrough-growth region 108, as already described in association withprevious embodiments.

Unlike the bone fixation/fusion device 10, the bone fixation/fusiondevice 100 includes at least one region associated with the body 106that, in contrast to the body 106, comprises a material that is subjectto more rapid in vivo bio-absorption or resorption by surrounding boneor tissue over time, e.g., within weeks or a few months. The resorbablematerial can comprise, e.g., polylactic acid (PLA), polyglycolic acid(PGA), poly(lactideglycolide) copolymers, polyanliydrides, cyclode,cirsns, polyorthoasters, n-vinyl alcohol, or other biosorbable polymersor like materials known or recognized in theprosthetic arts as havingsuch characteristics. The bio-absorbable region is intended tofacilitate implantation or placement of the body 106, but over time beabsorbed to minimize the footprint of the implanted device 100 in thelong run.

The bioabsorbable region or regions can possess functionality to aid inthe implantation process. For example, as shown the illustratedembodiment, there are two bioabsorbable regions 102 and 104. Region 102comprises a bioabsorbable screw region 102, which is desirably threadedor otherwise suitably configured to pierce bone and facilitateadvancement of the device 100 into bone. The other region 104 comprisesa bioabsorbable head region 104, which is desirably configured to matewith an installation instrument, (e.g., a screwdriver, to furtherfacilitate advancement and positioning of the bone fixation/fusiondevice 100 in the bone. The bioabsorbable head 104 may also be sized andconfigured to temporarily anchor the device 100 within bone, e.g., thehead 104 may be a slightly larger diameter than the body 106 of thedevice 100. The bioabsorbable screw portion 102 and head portion 104 areconfigured to provide an immediate benefit during the initial placementor position of the device 100, but over time be resorbed when they haveserved their initial purpose during implantation. This leaves the moredurable and less resorbable body 106 behind, to serve its longer-termfunction of stabilizing the fracture or fusion site.

As previously disclosed, a given bone fixation/fusion device can takevarious shapes and geometries. For example, as shown in FIGS. 18A and18B, the bone fixation/fusion device 200 possesses a flattenedrectangular (or wafer-like) configuration. A region 12 of the device 200can be textured or treated, as previously described, to provide bonyin-growth or through-growth. The bony in-growth or through-growth region12 may extend along the entire device 200 (see FIG. 18A) or along anyportion or portions of the device 200 (see FIG. 18B).

The bone fixation/fusion device 200 is desirably sized and configured tobe positioned to join two or more adjacent bone segments 14 (which cancomprise a fracture site, a fusion site, or both), as FIG. 19 shows, tofix and to promote the fusion of the adjacent bone segments 14. Thedevice 200 may also be sized and configured to fix and to promote fusionof multiple bone segments 14 or compound fractures, as FIG. 20 shows.FIG. 20 illustrates placement of the bone fixation/fusion device 200sized and configured for the fixation and fusion of, for example, afirst cuneiform (CE1), a second cuneiform (CE2), a first metatarsal(M1), and a second metatarsal (M2).

As shown in FIG. 20, one or more auxiliary fixation elements, such asconventional orthopedic screws 206, may also be placed within and/oracross the bone segments 14 by conventional techniques, to augment thestabilization of the bone segments 14 during the fusion process.

The size and configuration of the bone fixation/fusion device 200 may bemodified or adjusted in diverse ways to serve the intended stabilizationfunction in diverse bone locations, bone geometries, or bone types,which are intended to be fused or repaired. The bone fixation/fusiondevice 200 can come in a family of different pre-established sizes andshapes, or it can be individually sized and configured to meet therequirements of a particular individual's anatomy. For the sake ofillustration, by not limitation, a given bone fixation/fusion device 200may take the form of a disc (FIG. 21A), a square (FIG. 21B), or an oval(FIG. 21C). The height, width, and length of a given bonefixation/fusion device 200 may be varied depending on the specificlocation and amount of bone to be crossed for stabilization. A givenbone fixation/fusion device may possess a symmetric geometry, or anasymmetric or complex geometry—such as an L shape (FIG. 21D), a triangle(FIG. 21E), or rectangle with a triangular ends (FIG. 22F). Anycombination of linear or curvilinear or rounded geometries is possible.

As before described, a given bone fixation/fusion device can becannulated to aid in guidance during placement or implantation. Forexample, as shown in FIGS. 18A and 18B, the device 200 can include apair of opposing guide bores 202. The guide bores 202 are sized andconfigured to accommodate passage of guide pins 204, which are securedat the intended site of fixation/fusion device 200 can be guided by thepins 204 to the intended bone placement site.

To aid in stabilizing a given bone fixation/fusion device within bone,the device may be profiled. For example, as shown in FIG. 22A, the bonefixation/fusion device 200 may vary in height across its entire lengthof the device 200, to form a tapered wedge. Alternatively, as shown inFIG. 22B, the bone fixation/fusion device 200 may vary in height at oneend only. In these arrangements, the bone fixation/fusion device 200 isdesirably positioned with the area of greatest height in the proximaldirection, which serves to wedge the device 200 into place within bone.

To also aid in stabilizing a given bone fixation/fusion device withinbone, the device can include one or more anti-rotational elements, whichfurther stabilize and secure the device in the desired position withinbone. The size and configuration of the anti-rotational elements mayvary. For example, the anti-rotational elements may comprise an array offins 300 projecting from a stem-like device 10 (FIG. 23A), or an arrayof grooves 302 formed in a rectangular wafer device 200 (FIG. 24), orwings 304 formed in a rectangular wafer device 200 (FIG. 25), or flanges306 projecting from a wafer device 200 (FIG. 26). The anti-rotationalelements can comprise (see FIG. 23B) an array of bumps 308 or surfaceprojections 310 formed on all or a portion of the device, which can beeither stem-like or wafer-like in its configuration. Any number ofanti-rotational elements, or any configuration of anti-rotationalelements, or any combinations of configurations can be provided to servethe functional objective of stabilization.

As also previously described, two or more bone fixation/fusion devices200 of the types generally described above may be assembled to form acomposite bone fixation/fusion device having a desired size andconfiguration. For example, in the arrangement shown in FIGS. 27 to 29,the bodies of two bone fixation/fusion devices 200 each have a slot 208.Slot 208 in a first device 200 mates with a like or complementary slot208 in a second device 200 to permit the assembly of a composite bonefixation/fusion device 310, which has a crossed, anti-rotationalconfiguration for placement across bone segments 14. The crossedrelation of the composite bone fixation/fusion device 310 has anincreased surface area and adds further stability to the devices 200 inbone during the fusion process.

It will be apparent to one of skill in the art that the location, size,and configuration of the slots 208 may be varied to accommodate specificneeds and a specific anatomical location as well as individual anatomy.It is also apparent that other mating configurations, e.g., groove andtab fitments, or snap-fit arrangements, or Morse taper fits, or threadedassemblies, can be used to assemble two or more bone fixation/fusiondevices into a composite device 310.

As shown in FIGS. 30, fixation or gripping plates 212 may be fitted to agiven bone fixation/fusion device. In the arrangement shown in FIG. 30,the body of the bone fixation/fusion device 200 includes one or moreattachment sites 210, e.g., slits or indentations, which are sized andconfigured to receive a selectively removable fixation or gripping plate212. When received within the slit 210, the plate 212 extends radiallyfrom the device to grip into bone and further secure the device 200within bone.

In an alternative embodiment, shown in FIG. 31, the attachment site 210can include a tab 214, which mates with a notch 216 in the fixationplate 212 to secure the plate 212 within the device 200.

Other forms of interlocking or nesting configuration can be used. Forexample, tongue-and- groove fitments, or snap-fit arrangements, orthreaded fitments, or Morse taper assemblies can be used to assemble oneor more fixation or gripping plates to a bone fixation/fusion device.

The fixation or gripping plate 212 is formed of durable biocompatiblemetal or bone substitute material, as previously described. In somecases, it may be desirable to provide a bony in-growth surface on atleast a portion of the plate 212. Alternatively, the plate 212 may beformed of a bio-absorbable material, as already described.

FIGS. 30 and 31 illustrate embodiments in which the plates 212 present agenerally blunt and flat configuration. It will be apparent to one ofskill in the art that, however, that the plates 212 may also provide asharpened or cutting edge or be otherwise sized and configured asnecessary to accommodate specific location and individual anatomy. Forexample, the plate 212 may be rounded (FIG. 32) or tapered (FIG. 33).

FIG. 34 illustrates an alternative embodiment in which one or morefixation ridges 218 extend radially from the bone fixation/fusion device200. Similar to the fixation plates 212, the ridges 218 may be variouslysized and configured so as to grip into bone and further secure the bonefixation/fusion device 200 within bone.

Fixation elements can be formed in situ. For example, as shown in FIG.35A, a bone fixation/fusion device 200 can include a malleable region320 that normally presents a low-profile conducive to implantation. AsFIG. 35B shows, the profile of the malleable 320 can be changed in situafter implantation to a radially enlarged or extended profile 326 thatprovides stabilization or an anti-rotational function to the device 200.In the illustrated embodiment, the malleable region 320 is slotted (seeFIG. 35A) to accommodate placement of a wedge tool 324 carried formanipulation by a stylet or cannula 322 (see FIG. 35B). The wedge tool324 flays apart the slotted malleable region 320 (as FIG. 35B shows), tocreate the enlarged profile 326 for stabilization and/or rotationresistance.

In use, and with reference to FIG. 36, pilot holes 220 are drilled intoadjacent bone segments 14 (e.g., along a fracture line in a single boneor between adjacent segments of different bones) by conventionalsurgical techniques. In the illustrated embodiment, a single pilot hole220 is drilled into each bone segment 14. It is to be understood thatthe number and configuration of the pilot holes 220 may vary asnecessary or as desired.

As shown in FIG. 37, the physician can then then saw, using conventionalmethods, between the pilot holes 220 to prepare a cavity 222 to receivethe device 200.

Guide pins 204 may, if desired, be placed at opposing ends of the boredcavity 222, as seen in FIG. 38. In this arrangement, as shown in FIG.39, the selected bone fixation/fusion device 200 is passed over theguide pins 204 to position the device 200 with the cavity 222. The guidepins 204 may then be removed. In an alternative arrangement, guide pins204 need not be used, and the device 200 is manually inserted by thephysician into the bore cavity 222.

An alternative embodiment is illustrated in FIGS. 40 and 41. In thisembodiment, a c-shaped restraint 224 is placed against each end of thebored cavity 222. The selected bone fixation/fusion 200 is thenpositioned between the restraints 222 such that the restraints 222engage the device 200 to secure the device 200 within bone.

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

What is claimed is:
 1. A method comprising: identifying a bone sitecomprising a first bone segment, a second bone segment, and a jointbetween the first and second bone segments; providing an elongated bonefusion device having a longitudinal axis and a rectilinear cross sectiontransverse to the longitudinal axis and including an exterior surfacetreated to provide bony in-growth; forming a bore in the first bonesegment; forming a bore in the second bone segment that faces the borein the first bone segment across the joint, the bores in the first andsecond segments each being non-parallel to the joint and sized andconfigured to tightly engage the exterior surface of the elongated bonefusion device; and fusing the joint by inserting the elongated bonefusion device across the joint and into tight engagement within thebores of the first and second bone segments, to thereby restrictmovement of the elongated bone fusion device across the joint andprovide bony in-growth within the bores along the exterior surface ofthe bone fusion device.
 2. A method according to claim 1, wherein therectilinear cross section of the elongated bone fusion device comprisesa square.
 3. A method according to claim 1, wherein the rectilinearcross section of the elongated bone fusion device comprises a rectangle.4. A method according to claim 1, wherein the rectilinear cross sectionof the elongated bone fusion device comprises a triangle.
 5. A methodaccording to claim 1, wherein forming the bore in the first bone segmentcomprises drilling a pilot bore with a drill bit.
 6. A method accordingto claim 1, wherein inserting the elongated bone fusion device acrossthe joint comprises tapping the bone fusion device.
 7. A methodcomprising: identifying a bone site comprising a first bone segment, asecond bone segment, and a joint between the first and second bonesegments; providing an elongated bone fusion device having alongitudinal axis and a cross sectional profile transverse to thelongitudinal axis that is defined by at least one apex, wherein theelongated implant structure comprises an exterior surface region treatedto provide bony in-growth; forming a bore in the first bone segment;forming a bore in the second bone segment that faces the bore in thefirst bone segment across the joint, the bores in the first and secondsegments each being non-parallel to the joint and sized and configuredto tightly engage the exterior surface of the elongated bone fusiondevice; and fusing the joint by inserting the elongated bone fusiondevice across the joint and into tight engagement within the bores ofthe first and second bone segments, to thereby restrict movement of theelongated bone fusion device across the joint and provide bony in-growthwithin the bores along the exterior surface of the bone fusion device.8. A method according to claim 7, wherein the cross sectional profile isdefined by three apices.
 9. A method according to claim 7, wherein thecross sectional profile is defined by four apices.
 10. A methodaccording to claim 7, wherein inserting the elongated bone fusion deviceacross the joint comprises tapping the bone fusion device.